1. A school has 25 classes. After cleaning today, 200 tons of garbage were dumped. How much garbage does each class take out on average?

One hundredth of a ton =5 kg

5÷25= one fifth (kg) =200 grams.

Licun planted 20 hectares of peanuts this year, including four fifths of corn and three fourths of soybean. How many hectares of soybeans are planted?

20× 3/4 = 15 (hectare)

There are 90 sixth-grade students in bright primary school, which is one sixth less than that in fifth grade. How many students are there in Grade Five?

90÷ (1-1/6) =108 (person)